Hydraulic transmission



Oct.'24, 1939. R. w. EMERSON HYDRAULIC TRANSMISSION Filed April 2l, 1939Patented Oct. 24, 1939 UNITED STATES PATENT OFFICE 3 Claims.

AThis invention relates to hydraulic transmissions capable of use inautomobiles, busses, trucks and other kinds of traction machinery, andmore 4particularly to variable speed transmissions of the type in whicha iiuid is employed for operating a plurality of pistons by which adriven shaftV is coupled for rotation to a drive shaft, the speedrelationship between the drive and driven shaft being subject to controlby the operator.

i0, An object of my invention is to provide an improved form ofhydraulic transmission of the above character. y

yOther objects and advantages will be apparent from the followingdetailed description of a prelli; ferred vform ofthe invention,reference being had tothe annexed drawing, in which:

Figure l is an end view, in part cross-sectional, of a transmission inneutral position;

f Figure 2 is a partly cross-sectional view taken at right anglesthrough the transmission of Fig. 1;

Figure 3 is a detail View of the valve-operating mechanism;

,Figurefl is an end View, in part cross-sectional, of theftransmissionof Fig. 1 in full speed operating position; p

Figure 5 is a partly cross-sectional view taken at right iangles throughthe transmission in the position of Fig. k4;

Figure 6 is a detail view showing the manner in 3o which the drivenshaft is adapted to be associated with vthe drive shaft for independentrotation;

and

Figure 7 is a detail view of the transmission operating plate.

Y. Referring to the mechanism illustrated schematically in the drawingin which a drive shaft I operated from an engine or motor is adapted tobe coupled to a driven shaft 2 through the transmission of my invention,the drive and driven shafts .are supported in xed bearings 3 and 3arespectively. yThe end of the driven shaft-is adapted to telescope overthe end of the drive shaft, as indicated inFig. 6, sogthat these shaftsmay rotate independently of each other. Fixed upon the driven shaft soVas'to rotate therewith is a ny wheel disk 4 having secured thereto atangularly spaced points adjacent its circumference, cylinders 5(numbering two in the present embodiment but which may be, increased inrnumber if desired) connected by a pipe or conduit 6 skirting the disk 4.

The cylinders and pipe are filled with a fluid, such as oil, and theflow of the fluid between the cylinders is controlled by a valve 'Ifastened to the 4disk 4 and having a stem Ia which by rotation variesthe size of an orifice interposed in the pipe 6.

Fixed upon the drive shaft I so as to rotate therewith is a cam 8.Encircling the cam and extending outwardly therefrom is a pair of con- 5necting rods 9. Each` of the cylinders 5 is provided withva piston I0reciprocable within the cylinder and in a direction radially withreference to 'the axis of rotation of the drive shaft I. A rocking leverI I is pivoted to the outer end of each l0 connecting rod and this leveris provided with an arcuate slot I Ia described from the axis of thedrive shaft I as a center. Pins la carried by the pistons pass throughtheir corresponding slots in the levers. .15

The outer ends of the leversthat is, the ends of the levers remote fromtheir pivotal connections with the connecting rods B-are provided withholes which receive the ends of fingers I3 projecting outwardly from oneface of a transmission 20 operating plate I4. These fingers pass throughclearance openings 4a in the disk 4. The plate I4 is formed integralwith a sleeve I5 surrounding the driven shaft and independentlyrotatable with respect thereto. For rotating the plate I4 25 through alimited arc with reference to the driven shaft 2, the sleeve is formedwith a pair of longitudinally inclined grooves I5a. A collar I6 looselyencircling the sleeve I5 is provided with keys I6a passing through theinclined grooves I5a and 30 receivable within a pair of straightlongitudinallyextending grooves I5b on driven shaft 2. 'I'he keys.impart angular displacement to the sleeve relative to the driven shaftwhen the collar is moved along the sleeve I5 by means of a control 35rod I'I slidable through a boss 3b upon fixed bearing 3a and adapted tobe operated either by hand or by foot.

t VIn order to actuate the valve 'I through movement of the plate I4aslotted arm I 8 projects from 40 one face of plate I4 and within theslot is received the outer end of a control lever I9 secured to thevalve; stem 'Ia and passing through a clearance opening in disk4.Rotative `movement of the plate in either direction causes the controllevers 45 to be turned in corresponding directions to vary the valveopening, or to completely open and close such opening. u l

Plugs20 aresuitably provided in the tops of the cylinders 5 forintroducing uid into the trans- 50 mission system when necessary. Themechanism described above preferably will be enclosed within a casing(not shown) containing oil for the lubrication of the parts.

The operation of the hydraulic transmission 55 described above is asfollows: With the cam 8 occupying the position indicated in Fig. 1, thetransmission will be in neutral; that is, the drive shaft I will rotatewithout imparting rotation to the driven shaft 2. In this position thepistons 5 are motionless and the valve 'I wide open. The connecting rodsat this stage will be angularly offset by about 45 degrees from a lineconnecting the pistons with the center of rotation of the drive shaft I(and cam 8) and hence rotation of the cam will idly rock the levers 'II, fastened to the ends of the connecting rods 9, upon the fingers I3.

When the control rod II is pushed forward carrying with it the collarI6, the sleeve Il5 and transmission operating plate I4 are rotated,causing the fingers I3 to shift the rocking levers Il in a clockwisedirection (considered with reference to Fig. 1) and consequently movingthe connecting rods 9 more in line with thev pistons I. The rockingmovement of the levers'now transmits a reciprocating Vmovement to thepistons, the maximum stroke of the pistons being reached when theconnecting rods are in line with the pistons, as illustrated in Fig. 4.

Y -As 'the plate I4 is rotated the valve 1 will be gradually closed asalready described in consonance 'with such movement. This producesfrictional resistance tothe flow of iiuid between the cylinders 5through the pipe 6 and tothe travel of the pistons within the cylinders.The thrust exerted by the pistons against the fiuid within the cylinderstends to vlock the fly wheel disk to the cam, causing the latter to turnwith the cam, so that when the plate has reached its maximum position ofdisplacement (the full speedposition) as indicated in Figs. 4 and 5, thefly wheel 'disk vand the cam, and hence the driven shaft and the driveshaft, rotate at the same speed.

When the control rod I'I is pulled rearwardly toward the position shownin Fig. 1, the levers Il are shifted counterclockwise and the valve 'lis gradually opened to decrease the resistance to the flow of iiuidbetween the cylinders. Hence the speed of the driven shaft is reducedrelative to the drive shaft.A VComplete retraction of the control rodrestores the transmission to the condition shown in Figs. 1 and 2.

While I have described and illustrated a hydraulic transmissionincluding two cylinder and piston assemblies, it will -be apparent thatthe number Vof such cylinders and pistons may be increased if desired.Likewise, more than a single valve to regulate theflow of fluid betweenthe cylinders may be employed if necessary or desirable.

The invention may be embodied in other lspeciiic forms without departingfrom the spirit or essential characteristics of the invention,fand `thepresent embodiment is `therefore to be con- Asiolered as illustrativeand not restrictive and all angularly spaced apart and radially locatedwith reference to the common axis of rotation of said shafts, pistonsreciprocable within the cylinders, a conduit providing communicationbetween the cylinders, a fiuid filling the cylinders and conduit, avalve for Varying the iiow of iiuid through the conduit, a cam fixedupon the drive shaft, connecting rods freely encircling the cam, arocking lever extending between each connecting rod and a piston, theconnection of the rocking lever with its piston being adjustable alongsaid rocking lever, a fulcrum for each rocking lever, and means forangularly shifting the fulcrums of the rocking levers about the driveshaft so as to move the connecting rods into and out of alignment withthe pistons and for simultaneously controlling the valve. Y 2.Ahydraulic variable speed transmission for operatively coupling a drivenshaft to an aligned drive shaft, comprising a plurality of cylindersiixedly supported upon the driven shaft and angularly spaced apart andradialy located with reference to the common axis of rotation of saidshafts, pistons reciprocable within the cylinders, a conduit providingcommunication between the cylinders, a .fluid filling the cylinders andconduit, a valve for varying-the flow of iiuid through the conduit, acam fixed upon the drive shaft, connecting rods freely encircling thecam, a rocking lever extending between each connecting rod and a piston,the connection of the rocking lever with its piston being adjustablealong said rocking lever, a .transmission operating member rotatablyadjustable about the driven shaft and providing fulcrums for the rockinglevers, and means for angularly shifting the transmission operatingmember to move the connecting rods into and outY of alignment with thepistons and simultaneously controlling the Valve. 3. A hydraulic,variable speed transmission for operatively coupling a driven shaft toan aligned drive shaft, comprising a fly wheel disk secured to thedriven shaft, a plurality of cylinders iixedly supported radially and inangularly spaced relation upon the iiy wheel disk, pistons reciprocablewithin the cylinders, a conduit providing communication between thecylinders, a fluid filling the cylinders and conduit, ia valve upon theiiy wheel disk for varying .the `flow of fluid through the conduit, acam fixed upon the drive shaft, connecting rods freely encirclingthecam, a rocking lever extending between each connecting rod and a piston,said rocking levers each having an arcuate elongated `slot therein toprovide an adjustable pivotal connection with a piston, a transmissionoperating plate rotatably adjustable about the driven shaft, Viingersprojecting laterally from a face of said plate and providing fulcrumsfor the rocking levers, said fingers passing through slots 'in the riiywheel disk, acontrol lever on the valve, 'an arm on the transmissionoperating plate adapted to Uengage and operate said control lever, andmeans `for angularly shifting the transmission 'operating plate to movethe connecting rods into and out of alignment with the pistons Vandsimultaneously controllingthe valve.v

ROCKWELL W. EMERSON.

